Conventional inkjet printing apparatuses (hereinbelow simply referred to as “printing apparatuses”) perform printing on a printing medium while consuming ink supplied from an ink supply unit. When ink has been exhausted from the ink supply unit, many of the inkjet printing apparatuses continue printing on the printing medium without notifying a user of the ink exhausted status even if printing is not normally performed. Recently, however, an increasing number of printing apparatuses notify a user of an ink exhausted status if the ink has been exhausted, and urge the user to replace the ink supply unit.
As a residual-ink amount management system to detect exhaustion of ink from ink supply unit, the following systems are known.
(1) Ink-consumption amount information is counted every time ink is consumed and the information is stored in a memory. When a count value becomes a value indicating an assumed ink exhausted status, a user is notified of the status and urged to replace the ink supply unit. Then the user replaces the ink supply unit, and the user himself/herself voluntarily sets the printing apparatus to an ink-filled status.(2) Ink-consumption amount information is counted every time ink is consumed and the information is stored in a memory. When a count value becomes a value indicating an assumed ink exhausted status, a user is notified of the status and urged to replace the ink supply unit. On the other hand, the replacement of ink supply unit is automatically detected, and the apparatus is set to an ink-filled status.(3) Physical ink present/absent status is detected, and when the ink has been exhausted, a user is notified of the ink exhaustion and urged to replace the ink supply unit. Then, when the ink supply unit has been replaced and the presence of ink is detected, the apparatus is automatically set to an ink-filled status.
However, the above-described conventional residual-ink amount management systems have the following problems. The problems will be described in correspondence with the above systems (1) to (3).
System (1)
In this system, in a case where the ink supply unit has been replaced, since the user himself/herself voluntarily sets the apparatus to the ink-filled status, if the user forgets the operation, the residual-ink amount management cannot be properly performed. Further, even though the user does not forget the operation, it is considerably troublesome for the user to voluntarily set the apparatus to the ink-filled status.
Further, in this system, as the amount of ink consumed during a period from the point where the user replaced the ink supply unit to the point where the user voluntarily sets the apparatus to the ink-filled status is not considered, this ink-consumption amount becomes an error in the ink-tank residual amount management.
Further, if the amount of ink in the new ink supply unit is different from an assumed amount upon replacement of ink supply unit, the accuracy of the residual-ink amount management is further deteriorated.
System (2)
In this system, the replacement of ink supply unit can be automatically detected, however, it is not determined that the ink status has actually become a predetermined status. If the amount of ink in the new ink supply unit is different from an assumed amount upon replacement of ink supply unit, the accuracy of the residual-ink amount management is deteriorated.
System (3)
This system is excellent as a residual-ink amount management system, however, to detect the physical ink present/absent status, an expensive residual-ink amount sensor is required. Thus the system itself is expensive.